<button type="button" class="btn btn-primary"
        (click)="isCollapsed = !isCollapsed">Toggle collapse
</button>
<hr>
<div (collapsed)="collapsed($event)"
     (expanded)="expanded($event)"
     [collapse]="isCollapsed"
     class="card card-block card-header">
  <div class="well well-lg">Some content</div>
</div>
